A wreckage of a burnt car following a bomb explosion outside a police station in a Christian quarter of Damascus' Old City on October 21, 2012. (AFP Photo / SANA) / AFP

At least 13 people have been killed and 29 injured as a powerful blast hit outside a police station in Bab Touma neighborhood in the old part of Damascus, reports the state news agency. It comes as Lakhdar Brahimi visits the Syrian capital for talks.

Smoke rose above what were believed to be twin car bomb explosions in front of a police station, witnesses said. Other reports suggest it was a taxi rigged with explosives.

Ambulances were seen rushing to the scene as police shut access to the area, Twitter user NMSyria says.

At least 13 people were killed by the blast, SANA reported citing sources in the Interior Ministry. But given that the area is usually crowded, there are fears the death toll could be much higher. It is also unclear whether any police staff are among those dead or injured.

Dozens of cars were burnt and many houses sustained extensive damage.

The area was busy at the time of the explosion, with people returning from Sunday prayers. Bab Touma is a predominantly Christian neighborhood. It is also a popular shopping place in Damascus.

Two more bombings were reported to have occurred in Syria on Sunday. An explosive device, planted “by terrorists”, detonated on a road in the capital’s neighborhood, injuring several passers-by. A suicide bomber blew up his car outside a Syrian-French Hospital in the besieged city of Aleppo. The latter instance resulted in material damage only, SANA said.

Syrians dousing a car following a bomb explosion outside a police station in a Christian quarter of Damascus' Old City on October 21, 2012. (AFP Photo / SANA)

Meanwhile, the UN-Arab League peace envoy Lakhdar Brahimi arrived in Damascus on Sunday for talks. The envoy met with President Bashar al-Assad in a bid to implement a ceasefire by next week, when the Muslim festival of Eid al-Adha begins.

“I appeal to everyone to take a unilateral decision to cease hostilities on the occasion of Eid al-Adha and that this truce be respected from today or tomorrow,” Brahimi told reporters in Damascus after meeting with Assad on Sunday.

Brahimi had previously met with Syrian opposition groups inside and outside the country. He said that while he "found an overwhelming response" from Assad's opponents to his cease-fire plan, he only received "promises" without "commitment".

The peace envoy did not reveal Assad's response to his plan. But SANA news agency says Assad assured Brahimi that he supported his mission: "The president said he is open to any sincere effort to find a political solution to the crisis on the basis of respecting the Syrian sovereignty and rejecting foreign interference."

Assad also stressed that a political solution must be "based on the principle of halting terrorism, a commitment from the countries involved in supporting, arming and harboring terrorists in Syria to stop doing such acts," the state news agency reported.

Whether Assad has in fact committed to the peace plan remains unclear, however.

Officials in Damascus blame the popular uprising that began in March of last year on a foreign conspiracy. They say the revolt against the government is an insurgency headed by "terrorists" who infiltrated the country from across the border.

The end of fighting in Syria all depends on the will of the countries that are backing the rebels and giving them arms, money and means of communication, believes Dr Ali Mohamad, the editor-in-chief of the Syria Tribune media channel, as “the rebel groups are all controlled from the outside”.

“These countries can make the rebels cease fire in 48 hours or even less – if they have the will to cease fire,” Mohamad insists.

The UN estimates the conflict in Syria has left over 20,000 people dead, while various opposition groups claim the death toll now stands at 33,000. Over 340,000 refugees have fled the country.

A Christian quarter of Damascus' Old City on October 21, 2012. (AFP Photo / SANA)

A Christian quarter of Damascus' Old City on October 21, 2012. (AFP Photo / SANA)

A wreckage of a burnt car following a bomb explosion outside a police station in a Christian quarter of Damascus' Old City on October 21, 2012. (AFP Photo / SANA)

The neighborhood of Bab Tuma where the explosion took place.(Image from twitter user @NMSyria)